[Closed] Does suspension cause stutter bumps?

*inserts tounge into cheek*
Braking bumps are caused by mincers. And mincers, almost without fail, ride Lapierre Spicys, Specialized Enduros and Trek Remedys.

Blame the riders, not their bikes. 😉

Yup, dragging brakes and an increase in traffic, in all likelyhood. I'm always amazed at 24hr races how quickly braking bumps appear from nowhere, for no apparent reason.

The only thing I would add to this is that the aforementioned mincers' bikes let the mincers ride down things they might not otherwise have tried, and their lack of skills then means muchos skidding and braking bumps.

So in a way it's the bike, but mostly it's the mincers.

Braking. Suspension might be indirectly at fault by helping people to go faster in the first place, I suppose.

Sadly it is the reason that you need to think hard before putting resources into building a section of trail that is at all steep. The surface doesn't last long because of braking bumps.

On the 'DH' trail at CwmCarn, they've used that plastic honeycombe style matting to surface the run in to steep corners.

That certainly stops any braking bumps. Or any braking at all, for that matter, as it's so slippery.

Just blame whatever you've got an axe to grind about.

Full-sus bikes, mincers, fat tyres, Oranges, 29ers - it's what everyone else seems to do on here.

So I'm right to be a bit miffed then? I mean we were hooning down there in the days when 63mm travel was rad and discs hadn't even been born.

I like to climb back out of trails like that, and the top used to be hard, the balance of keeping the front down and rear under traction was key, now it's fubbered.

Edit, everyone knows I'm an old mincer, but I've never needed to brake on that before. It was always a drop in followed by a gentle rise that naturally scrubbed the speed off.

Why is it braking bumps are always the same size and shape?
I wondered if this was caused by the compression and extension of the forks under braking

The mechanism is probably more force onto the front wheel whilst braking equals more ground pressure.

To expand on my post, i mean the deep ripples repeating at about a foot apart

Just blame whatever you've got an axe to grind about.

You know, my axe is ground almost down to a little nub, I'm going to complain about that.

Effing steel axes, the old granite hammers didn't wear down like this :shakes head:

I recall having a long (and thrilling!) discussion about this on BM years ago. The consensus was that it was probably hardtails that tended to start them (as the back wheel skipped/locked over slight undulations in the trail under hard braking) but then it was full susser that probably made them worse as they followed the trail so any lockup would dig the holes deeper and deeper.

To expand on my post, i mean the deep ripples at about a foot apart

Pure conjecture, but hard braking tends to cause a single dip to form. Dragging brakes over the dip causes another dip to form as the suspension rebounds into and wheels relock as the bike thumops back into the ground, so a second dip forms. Repeat ad nauseum and wuith many many bikes dragging brakes, so get a whole series. Pretty soon, people start dragging brakes earlier and earlier becuase the corner is now 'bumpy'. So you get a whole long set into the corner.

Braking bumps make the terrain more technical. Why is that a problem?

Because they spoil the flow of trails. You could just cover every trail with rocks otherwise and claim that you're making them more technical but most people would prefer better flow.

FWIW, I'd pretty happily ride smooth, flowing, rolling but very twisty trails all day long - that's where I really get my thrills.

Usually the problem isn't so much that the trail is no longer smooth to ride, more that it is no longer smooth to water. Once you have a sufficiently abrupt dip water will puddle and catch and then erosion starts in earnest. A durable, sustainable trail lets the water move slowly across and away from the trail.

Dunno about a lak of flow, they by default only appear in sections that are steep and fast, where you would be braking into a corner.

So your mincing and the the bumps arent letting you brake as much as you other wise would.

The labarynth at Swinley is full of braking bumps, doesn;'t ruin the flow one bit even on a hardtail as 90% of them are into corners with no real need to brake (or if there is, the lost speed in the bumps is suficient)

In my experience they often appear on flat trails too - just before a corner where you need to brake reasonably hard - eg somewhere that some people lock up.

They also definitely do affect flow since they're nicely front wheel sized more often than not and nice and deep once the rain/puddles have got to work making them increasingly deep.

Deffo ruined the flow, I suppose it's fine if you have plenty of travel and weren't the sort of person that actually ever rode uphill.

It's the same old thing, people see trails like that as only worthy of rolling down. It's like another local steep drop that's a great technical climb. But then some muppet cut a drop off into it so that was end of trying to nail it going up.
Plus both are natural trails not manmade.

TBF the labarynth is in WAY better repair than most of the examples I can think of or have ridden.

they are (I think) caused by rear suspension and non-floating calipers. As your suspension compresses, the rear wheel moves slower, which does something (i think causes your braking time to be longer) and enlarges braking bumps. The very first ripple is always caused by something else (say a root) though. Hardtails tend to smooth them out, as the back wheel hops onto the upslope, knocking it a little flatter each time

btw, none of the bumps in the UK are anything like as bad as a well worn alpine trail. End up having to find a high or low line most of the time just to try and keep momentum (normally before the lightest of corners anyway). landing a large gap to braking bumps is interesting, to say the least.

Yes the section of trail that is now covered in bumps is arrow straight, plus you can see ahead of you a very obvious rise/berm that would clearly slow you down. The stutters start just yards from the start of the drop in.
In fact it used to have such a nice flow you could do it on a crosser. The rest of the trail is still perfect BTW.

They are caused by suspension. As people wheels hit a bump, their suspension comes up and then down again further down the trail hence the stutter bumps.

They also appear on dirt roads that are driven on by cars - for the same reason. They can go on for miles as car wheels are always being driven, so it doesn't necessarily have to be from braking.

they are (I think) caused by rear suspension and non-floating calipers.

why on earth would suspension be to blame for brake bumps? if you go through the first bump on a hardtail, the rear will be bounced into the air a bit, and on reimpact with the trail, rear wheel all locked up (because you're braking), it'll scratch some soil away creating the next bump. rinse and repeat. if anything, rear suspension should reduce this tendency by smoothing the impact of the rear wheel.
the reason you get more bumps than you used to is because it's been a very very dry summer so far, more people ride, and thanks to better bikes and brakes, speeds for approaching corners are higher than they used to, so more and later braking takes place.

Have the trails seen a significant increase in traffic? I guess it is enevitible with more riders there will always be a proportion who mince about on the brakes, it tends to be a few riders coming in a bit heavy on the brakes causing that first ripple, which in turn forms a puddle, and the next time they approach their braking point shifts a foot back (now they are approaching a puddle/ripple before a corner) thus starting the creation of another ripple/bump….

I suppose you could argue that suspension has the knock on effect of allowing a poor rider to get to higher speeds than they would manage on a HT and then of course as they are braking too late/sharply from a higher speed they will displace more material and skid about causing more damage each time, so I guess bounce could be at least partly blamed, but in general an increase in traffic brings these trail wear problems out more...

Not knowing the details of the trail, is there any way you could make a feature out of the damaged section? A small kicker or exaggerate the ripples into a pump section to try and modify riders behaviour?
Would a trail repair accompanied by improved drainage help the issue or would it just be a sticking plaster solution?

cookeaa I wouldn't touch it as it's a natural trail, adding something like a kicker would not only ruin the aesthetics even more, but make it almost impossible to ride back up.
I think what annoys me is that a lot of riders adopt 'bike park' attitudes to natural trails to the point that I've even been told I'm going the wrong way WTF 😯
Perhaps it'll get better come winter I don't know, but yes for an area that's classic xc country there has been a huge influx of padded up visitors. And apart from the man made play area it's all rideable on a cyclocross bike.

tamworth, I was going to add the hardtail effect to my post but forgot 🙂

I think it's less though because under hard braking the rear wheel isn't on the floor much, and the front is pressed into the ground where the tyre will absorb the lumps etc.

I only ever remember one instance of braking bumps back in the fully rigid days. And they were minor and quite close together. The great big bumps on DH courses are on a different scale.

I thought it was something to do with the wheelbase shortening during travel, wasn't it refered to as suspension braking in the past?

Bumps? On an MTB trail you say?

Whatever next...? 🙄

round here you can get 'steps' on climbs where horses have all used the same place to put their hooves.

nothing moves soggy clay like a ton of horse.

Do you ride down near vertical trails PP? Or ones with car sized rocks on them? Why not? 😉

Remember 24" wheels on DH bikes? One of the reasons they never worked was because they'd drop into braking bumps and get slammed about all over the shop, far more than the 26" wheels that (mostly) created them. It seems that different wheel sizes create/fit different sizes and shapes of braking bumps. Is there some kind of resonance/frequency effect going on?

If so, your solution is to buy a 29er.

Do you ride down near vertical trails PP? Or ones with car sized rocks on them?

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Nothing but then neither does questioning the appearance of bumps on mtb trails 😉

Is there some kind of resonance/frequency effect going on?

Yes, in the case of stutter bumps made by cars on dirt roads.

Its not suspension, at least not directly. Braking bumps are erosion caused by a skidding wheel. Fat tyres, disc brakes and suspension means bikes can brake later and harder then they could previously. That's why braking bumps are a relatively new phenomenon

Nothing but then neither does questioning the appearance of bumps on mtb trails

Ahh. Maybe a slight misunderstanding. I'm not questioning the appearance of bumps, but having a tongue in cheek poke at those that want everything nice and smoooooth. 🙂

I like it bumpy, see? If I wanted smooth, I'd ride on the road. 😉

So you'd complain if someone smoothed it all out.

Just like I'd complain if someone made everything full of stutter bumps 😉

(would you really enjoy riding a trail of endless stutter bumps?)

My complaint is that it's ugly, unneccesary and turned the trail into a one way trail.

Edit and there are loads of false trails or run offs where people have gone too fast for their skill level.

[i](would you really enjoy riding a trail of endless stutter bumps?) [/i]

I rode across 3 ploughed fields on sunday, uphill, the bridleway was at 90 degrees to the direction of the ploughing.

After nearly a mile of riding on bone hard ridges the novelty wore off.

So you'd complain if someone smoothed it all out.

I'd think "why bother" to be fair. 🙂

would you really enjoy riding a trail of endless stutter bumps

That would be less boring than a perfectly smooth trail! 😉

I've never understood these damn things, other than it's skidding that causes them. And skids, as we know, are for kids.

I think it's a bit of all of the above. Beginners going too fast, panic-braking creating a groove, rain pooling, repeat.

However we need beginners or else we won't get investment in trails. So, a bit of education and ride wide if they annoy you.

al.

The real problem is overuse.

You really need free access to the countryside like in Scotland.

The proliferation of trail centres means that mountainbikes are getting more and more specialised around a groomed trail ethos. Berms? where do you find them on a real trail.

The proliferation of trail centres means that mountainbikes are getting more and more specialised around a groomed trail ethos. Berms? where do you find them on a real trail.

So? It's fine for ice-skaters to go round an ice rink all day, or skiiers to go up and down groomed pistes... so why not specialised MTBers?

You really need free access to the countryside like in Scotland.

You don't need to be in Scotland to not have to go to trail centres! 🙂